Quantum dots crack the influenza uncoating puzzle

One hundred years ago, the devastating 1918–1919 Spanish influenza pandemic took the lives of 50 to 100 million people, or 3 to 5% of the world population (1). Influenza A virus (IAV) pandemics occur when an animal IAV crosses the species barrier, usually by acquiring a new genetic trait by reassortment (2). According to the 2017 National Risk Register of Civil Emergencies of the United Kingdom, the predicted impact severity of a full-blown influenza pandemic is at the highest level; greater than that of coastal flooding (tsunami), major industrial accidents, and attacks on crowded places or transport. Has the advent of vaccines and antivirals truly increased our preparedness for the next influenza outbreak, as we struggle to predict which seasonal strains will circulate next winter? Needless to say, much is unknown about the cell biology of influenza infection and how the virus interacts with the multitude of host cellular processes that enable infection. Virus entry mechanics can be explored as a target for antiinfluenza therapy. To complement virus–host interaction studies using cell biology, biochemistry, and structural biology, robust live-imaging strategies that offer high temporal and spatial resolution are essential. However, the influenza RNA genome is intolerant to large genetic insertions, and efforts to rescue viruses using GFP fused to viral core proteins have had limited success (3). This has delayed progress in the field of influenza-entry live-imaging studies. In PNAS, Qin et al. (4) develop a nanotechnology that labels IAV viral ribonucleoprotein complexes (vRNPs) with quantum dots (QDs)—an approach that will advance the mechanistic understanding of influenza virus entry using live fluorescence microscopy.